A constant voltage power supply circuit incorporated in a semiconductor integrated circuit supplies a power supply having a stable voltage to an internal circuit. The constant voltage power supply circuit has an output MOS transistor, for example, and controls a gate voltage of the output MOS transistor on the basis of a difference voltage between a reference voltage and a feedback voltage obtained by dividing an output voltage, to make the output voltage constant.
The constant voltage power supply circuit described above has a problem that a rush current flows through the output MOS transistor when power supply is turned on.